The Octopus That Was Larger Than The Giant Squid

Added: 2026-05-06

[00:00:00]Another prehistoric giant is making waves across the internet, and no, it is not a theropod, sauropod, or even a dinosaur. It is not a mammal, nor one of the famous marine reptiles that usually dominate the discussions of the ancient oceans. This time, the spotlight belongs to something far stranger, and in many ways unexpected. According to a new 2026 study published in American Association for Advancement of Science, some of the earliest known octopuses may have grown to colossal sizes and risen to the highest levels of the Cretaceous food web. Today everybody, I'm your host bringing you another fossil video. And this one arguably involves one of the largest invertebrates to have ever been proposed. As always, make sure to like and subscribe to the channel, and comment down below your favorite marine animal. This animal is known as the Nanaimo toothus hagartorum, a giant early relative of modern finned octopuses. So giant, in fact, it may have rivaled some of the largest predators in its own ecosystem. Now, when most people think of octopuses, they imagine highly intelligent, but relatively modest animals hiding in reefs, opening jars, and squeezing through impossible gaps. Even when people think of the larger species, such as the giant Pacific octopus, it still seems small compared to what this study suggests once lived over a hundred million years ago. The story of this giant actually begins well before 2026.

[00:01:14]Important fossil material was first recovered in 2008 from late Cretaceous marine rocks on Vancouver Island, while additional specimens were known from the Cretaceous deposits in Japan. At first, these fossils were isolated cephalopod jaws, interesting, but not too much to go off of. But only a smooth 18 years later of taxonomic revision, technological upgrades, and digital imaging were researchers able to more confidently suggest that they were looking at a true giant. Now, that alone would be impressive, but what really makes this discovery remarkable is that octopuses almost never fossilize well.

[00:01:46]Unlike animals with bones or shells, octopuses usually vanish without leaving too much of a trace. In this case, the researchers had to rely largely on the fossil jaws or beaks of the animal.

[00:01:56]Also, quick note, this video I've been saying octopuses as the plural of octopus because, well, that's the correct way of saying it. But you all let me know what your preferred pronunciation is. Personally, I think octopi sounds better. Anyways, on the positive side, the jaws are pretty informative. In living cephalopods, beak size usually correlates strongly with body size, which, yeah, that makes sense on paper. The larger mouth that you have, it should be expected that the bigger your body will be. This allowed paleontologists to estimate the scale of this extinct animal. Through the researchers' methods, they were able to estimate the Nanaimo toothus may have reached a mantle length of roughly 1.6 to 4.4 m, or 5.2 to 14.4 ft. Now, for the mantle length, for those of you that may not be aware, is the measurement of the main body from the tip to the eyes.

[00:02:41]But I'm sure all of you are here for its total length. How truly big was this animal? Well, this octopus may have grown between 6.6 to 18.6 m in length.

[00:02:51]Now, for my American mates watching, that is 21 to 61 ft in length.

[00:02:55]Absolutely gigantic, as it would dwarf the famous giant squid by quite a bit.

[00:03:00]The article compares its larger size to other marine animals, and the seeming difference is evident. However, just because it is seemingly bigger in stature does not mean it is heavier. I mean, the colossal squid, which can reach over 10 m or 33 ft in length, are regarded as the heaviest living invertebrate species today. However, they still weigh under a ton in weight.

[00:03:19]So, while physically looking quite massive as a result of their tentacle length and its fins, it would still weigh less than the larger mosasaurs that would have called the oceans home.

[00:03:28]Now, it is important to be clear here that it is not a direct tape measure reading from the complete fossil.

[00:03:33]Obviously, as referenced before, we don't have the full skeleton because we simply can't. It is a scientific estimate based on the jaw proportions and body ratios in living relatives. But if those estimates are close to correct, then this animal would rank among the largest cephalopods ever known, greater in scale than the colossal and giant squid, and possibly being among the largest invertebrates yet described. The study places these animals within cirrata, the finned octopus lineage.

[00:03:58]Today, cirrates are mostly deep-sea octopuses, often being nicknamed Dumbo octopuses because of their eel-like fins on their mantles. These animals tend to be slow-moving, gelatinous, and relatively small compared with the active coastal octopuses. That makes this discovery all the more surprising.

[00:04:14]A group now associated with deep-sea drifters may once have included enormous predators patrolling shelf seas of the circum-North Pacific. The researchers also argue that these animals were not passive scavengers, instead being active hunters. This is supported by the fossil jaws, which show intense wear, including chips, scratches, polishing, and even cracks. In modern cephalopods, similar damage is associated with repeatedly crushing hard prey, such as shelled animals. In the largest jaws of these fossil octopuses, around 10% of the jaws' tip appears to have been worn away over time. That suggests that it was not just snacking on soft prey, but frequently feeding on tough, durable prey. With these interpretations, the authors believe that these octopuses may have acted as active carnivores, being capable of crushing shells and bones.

[00:05:00]However, I am not going to be so hasty to say that this means they were tangling with adult mosasaurs, as I personally don't think that would actually go well for them. But I believe it does suggest that they would have occupied a high trophic level and may have competed with major vertebrate predators in the same ecosystem. Still though, they would have been massively outweighed by mosasaurs. Another interesting detail that the researchers picked up is the asymmetry of the jaw wear. In both major species studied, the right side of the jaw appears to be more worn than the left. The authors of the article suggest that possible lateralized behavior, meaning the animal may prefer one side while feeding, could suggest intelligence. In living animals, behavioral laterality is often linked to more advanced cognitive capacity. For example, primates like chimpanzees, birds like parrots, and of course modern cephalopods like octopuses. Now, this does not act as hard proof of genius-level octopus planning, but it may hint that complex cognition was already emerging in early octopus evolution. And that broader evolutionary story may be the most important part of it all. For hundreds of millions of years, vertebrates have generally been viewed as the dominant apex predators of marine ecosystems. Sharks, marine reptiles, and later whales occupied the top tiers of ocean food webs. Sure, we may have the oddball here and there like the colossal squid, but the family seemingly gets the short end of the stick, usually being seen as prey or mid-level hunters, rarely as the top dogs. This study challenges that picture by proposing a giant octopus that would have briefly entered the same ecological niche. Now, as exciting as this all is, we all need to be very cautious.

[00:06:31]Paleontology has a long history of dramatic size estimates later being revised and downsized when new material or new measurement methods come to light. Look what has happened to spinosaurus, deinosuchus, and of course the dunk over the years. This octopus is not safe from the same treatment, and of course, since it is primarily known from jaws, not complete bodies, proportions must be reconstructed, and at times it means overestimations occur. The methods used are reasonable and grounded.

[00:06:57]However, there is such a big size range provided that it is hard to be confident. Additionally, the cephalopod paleontologist Christian Klug believes that the larger size estimates are on the extreme side, and I have seen other people debating the smaller sizes to be more reasonable. So, if it is something to remember, there are three things in life that are for sure. That being death, taxes, and prehistoric animal sizes being anything but stable. Still, even holding that caution high, the core interpretations from this study is pretty sweet if you ask me. We potentially have a giant, intelligent octopus that would have been hunting smaller marine reptiles. Clearly, the oceans of the late Cretaceous continuously get more and more unique.

[00:07:35]Alongside the dominant mosasaurs, plesiosaurs, giant sharks, and predatory fish, there may have also been a gigantic octopus armed with a crushing beak, powerful arms, and quite cognitively impressive behavior. And with that, we've reached the end of the video, and I hope you've all enjoyed.

[00:07:50]Let me know if you prefer this style being a bit less formal and shorter, or do you prefer the longer versions?

[00:07:55]Anyways, make sure to like and subscribe, and I'll catch you all in the next video. See you mates.